puberty

the changes that occur in boys and girls around the age of 10 to 14, which signify the beginnings of sexual maturity and the subsequent functioning of reproductive organs. It is apparent through the appearance of SECONDARY SEXUAL CHARACTERISTICS , such as a deepening of the voice in boys and growth of BREASTS in girls. In addition, girls commence MENSTRUATION and in boys the size of TESTICLES increases. In both sexes body shape changes noticeably and body hair grows. The changes are initiated by PITUITARY GLAND hormones acting on the ovaries ( see OVARY ) and testes.